Osprey CE Alloys Technical Information

Important technical information regarding CE Alloys. For the most current info please refer to the Sandvik Osprey Website.

If you would like a copy of the latest CE Alloys brochure please click here

Standard range of controlled expansion alloys

AlloysCTE
CE17F 17 ppm/°C
CE17MF 17 ppm/°C
CE13F 13 ppm/°C
CE11F 11 ppm/°C
CE9F 9 ppm/°C
CE7F 7 ppm/°C
CE6F 6 ppm/°C

Other alloys available are CE8F 8ppm/°C, CE13MF and development alloy CE5F 5ppm/°C.

Designation system

The designations for CE alloys are constructed using the following model: CE stands for Controlled Expansion. The number following after 'CE' (e.g. 7 in CE7) gives the room temperature CTE in ppm/°C.

F grades

'F' is added to the alloy type (e.g. CE11F) to identify a finer grade than was previously available for CE alloys, that is a grade with a finer microstructure, which improves the strength and weldability of the alloy. As the finer grades have more consistent mechanical properties without reducing the thermal properties, the F grade alloys are now substituted for all the grades of CE alloys.

M grades

The M grade alloys (CE17MF and CE13MF) contain small additions of iron (Fe), manganese (Mn) and magnesium (Mg), so that similar heat treatment to 6000 series alloys (Al-Si-Mg) produces hardening of the matrix. Originally, this was to improve the machinability of the alloys but it can also be used to improve the strength but at the expense of thermal conductivity

Mechanical properties for CE alloys

CE17FCE17MFCE13FCE11FCE9FCE7FCE6F
Mechanical properties, typical values
Composition Al-27%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al Si-20%Al
Tensile strength, ultimate ≥160  175-3123) 205 193  181 ≥100  N/A
Yield strength, MPa  100 282 147  189 - - N/A
Bend strength (three point), Mpa - - 300  300  300  270 3191)
Young's modulus, GPa  91.8  91.82)  101.9  121.4 118 129.2  130
Rigidity modulus, GPa  35.8  35.82)  42.22)  48.6 46  51.6 N/A
Poisson's ratio  0.28 0.282)  0.272)  0.29 0.29 0.26  N/A
Density, g/cc  2.6 2.6  2.55   2.51 2.47  2.43  2.352)
Hardness, Hv  60  75–1323) 90 - 230 - N/A

1) Test pieces 4 mm x 3 mm x 40 mm
2) Calculated values
3) Depending on heat treatment condition

Thermal properties for CE alloys

CE17FCE17MFCE13FCE11FCE9FCE7F
Coefficient of thermal expansion, ppm/ºC (typical values)
Composition1) Al-25%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al
100K–200K - - - 7.8 - -
200K–300K - - - 10.6 - -
100K–300K - - - 9.2 - -
-60–200ºC - - - 11.6 - 7.6
Room temp. 15.3 15.3 12.2 11.4 9.1 7.2
25–200ºC 17.1 17.1 13.7 12.3 10.2 8.3
25–300ºC 18.1 18.1 14.6  12.9 10.9  8.8 
25–400ºC  18.7 18.7 15.2 13.4 11.3 9.2
25–500ºC  19 19 15.5 13.7 11.4 9.7
CE17FCE17MFCE13FCE11FCE9FCE7F
Thermal conductivity, W/m.K (typical values)
Composition1) Al-25%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al
At -100ºC - - - - - 180
At -50ºC - - - - 1292) 140
At -0ºC - - - - - 135
At 25ºC 177.4 146.8 145 132 121 120
At 50ºC - - - - - 110
At 100ºC - - - - 125* 110
At 200ºC 151.2 146.5 - - 108* 100
At 300ºC - - - - 98* 88
At 400ºC - - - - 90* 80
At 500ºC - - - - 85* 75
Specific heat, J/kgºC 846.3 767.25 857* 754* 780* 785*

* Calculated values

Microstructure of CE alloys

In the molten state Si and Al are mutually soluble, whereas in the rapidly solidified condition there is minimal solubility of Si in Al (< 0.3%) and even less solubility of Al in Si. The products are true alloys rather than metal-matrix composites (such as AlSiC) as all the phases present originate from an homogeneous melt.

The Al phase is continuous up to ~ 85%Al. Over approximately 40% Si, the Si phase also becomes continuous, offering a co-continuous duplex alloy (similar to AlBe alloys).

The continuous Si phase produces a stiff alloy with low thermal expansion and low internal stresses, whereas the continuous Al phase enhances thermal conductivity and toughness and lowers electrical resistance.

Consequently, as the Al content is increased, electrical conductivity, thermal conductivity, strength, toughness, CTE and machinability are also increased. For these reasons, it is best to choose the highest Al content alloy that is acceptable for the application.

Although Sandvik can supply machined components with Si contents as high as 85% Si (i.e. CE5), the relative brittleness of this composition means whenever feasible it is often better to compromise on the exact expansion match required and use a lower Si content alloy. For example, Kovar* packages (with a CTE of ~ 7ppm/°C) have been successfully replaced with CE9, CE11 and even CE13.

*Kovar is a trademark of Carpenter Technology Corporation